Sensitive time delay relay



y 3, 1956 R. G. QUICK 2,745,024

SENSITIVE TIME DELAY RELAY Filed 001;. l, 1953 FIG.2. 77

INVENTUR ROBERT G. QUICK United States Patent SENSITIVE rnvin DELAY Berni Robert. G. Quick, West Caldwell, N. 3., assignor to the United States of America as represented by the decretary of the Navy seems The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to a time delay device and more particularly to a DArsonval sensitive reiay type arrangement of general application and more particularly for use in aircraft launched mines and similar ordnance devices wherein a rugged timing mechanism having a min imum of moving parts is desirable and in which the ability to Withstand severe shock such as from aerial launching, is a factor ofprime importance.

The invention further relates to a novel method of operating a sensitive relay of this type as a magnetically damped time delay.

Prior time delay mechanisms for'use in ordnance of this character have embodied motor driven timing.

switches, clock mechanisms or escapement type devices which inherently possess a plurality of moving parts and/or gears, the shafts for each of which must be capabie of withstanding the shock loadings of rough handling and launching in service use. Such devices also present a high degree of sensitivity to dust and foreign matter in these moving parts, with a resultant high probability toward component failure or apparatus malfunction.

The instant invention utilizes a sensitive relay mechanism for closure of the mine arming circuits or for providing pulsed signals of a time delayed nature for other electrical circuits used in the apparatus associated therewith. It utilizes a short circuited coil in a DArsonval type movement to provide a magnetically damped time lag of predetermined interval duration in the closure of the switch points of the relay. Additionally the device incorporates an electromagnetic set-and-rcset arrangement for movement of the moving contact from the closed circuit position thereof to a position at a predetermined distance from the fixed contacts for repetitive cycles of operation.

The device is equally well adapted for one shot operation, and continuous pulse type delay applications in which the delay unit serves as a heart for all timed 2,745,024 Patented May 8, 1956 cally damped time delay action in a relay type timing device.

One object of the instant invention resides in the provision of an improved mechanical movement device for time delay applications having a minimum of moving parts.

Another object resides in the provision of a time delay device of rugged construction and possessing a high ortier of immunity to shock.

It is another object to provide a magnetically damped time delay device adapted for a high order of uniform pulse cycles without maintenance.

It is a further object to provide a moving element type electrical time delay device possessing facilities for both automatically repetitive cycles and manually set operation by which the delay time of the manually preset actuations are selectively variable.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. l is a view in elevation of a relay type time delay device of the present invention with parts thereof broken away;

Fig. 2 is a sectional view in plan taken along line 2'2 of'Fig. 1';

Fig. 3 is a schematic diagram of the operational circuit relationship of a particular embodiment of the time delay device and which is adapted for automatic operation; and

Fig; 4 is a schematic diagram of another operational circiut utilizing the time delay relay of the instant invention.

Referring now to Figs. 1 and 2 of the drawings in which like reference characters refer to like parts, there is shown a moving coil type magnetic. time delay mechanism 1 which includes a pair of relay units 2 and 3. The relay 2 is of a character generally similar to a DArsonval sensitive relay movement. The relay 3 as hereinafter described in greater detail is of the conventional moving armature variety. The relay 2 generally comprises a fixed assembly of generally horseshoe shaped permanent magnet 4, mounted on the plastic or resin material base 5, by the machine screws 6, which are received in tapped holes or bushings provided in the base and a movable assembly positioned generally within the airgap of the horseshoe magnet.

The relay 2 further includes a movable coil assembly at 7 which carries the coil 12. It is mounted on the magnet 4 by screws or studs and nuts at 8 which are threaded into the base 5. This coil assembly is generally conventional for sensitive relay movements and comprises a mounting. frame or bracket 10 for the two pivot bearings 9 and 11 for shafts of the moving coil 12.

The moving coil 12 carries the moving contact arm 13 and contact 14 which normally engages the two stationary contact tips 15. The upper coil shaft 16 is maintained biased to a position to hold the moving contact 14 in engagement with the tips 15 by a hairspring 17 attached theretoas by a collar at 18. The outer coil of the hairspringis retained as by staking. or pinning in the slot at 19 in the rotatable arm 21 which is clamped to the frame or bracket 10 by a washer and nut assembly at 24. In the event one lead of the coil is connected to ground through the shaft 16 and spring 17, the movable arm 21 need not be insulated from the bracket. 10. In the event both of the terminal leads of the coil 12 are desired to be isolated from ground the arm 21 is insulated from the frame by an insulating washer at and the arm may take the form shown in Fig. 2 having a projection thereon which is shaped to form a terminal 22 to which the lead 23 is soldered or connected in a manner to electrically join the external terminal 26. The isolation of the upper bearing pivot 11 is accomplished through a bushing or concentric insert, not shown, of insulating material which is disposed between the bearing 11 and frame 11 in a conventional manner. Also the lower pivot may be insulated from the frame 115 if desired.

The angular position of the movable arm 21 determines the degree of bias of the movable contact arm 13 by the spring 17. The fit at the upper pivot of the arm element 21 wtih respect to the frame 10 is such as to allow movement of the arm 21 against the frictional resistance thereof with the elements 10 and 24 to provide a slight bias for controlled adjustment of the movable contact against the fixed contacts as produced by hairspring 17. Some calibration of the time delay may be accomplished by varying the initial pressure of the movable contact against the fixed contact.

The lower coil shaft arrangement is generally similar to that of the upper unit except that the spring efiect may be omitted and the elements take the form of a spiral 27 of fine beryllium copper wire or the like to provide electrical connection through lead 28 to the other coil terminal of coil 12 from the frame mounted terminal 29.

The second relay 3 is of conventional design, and incorporates an electromagnetic coil winding 31 over a core piece 32 mounted on the base block 33. The bracket 34 is also mounted to this block 33 and serves as a mounting for the pivots 35 of the movable armature 36.

This relay 3 is arranged to drive a set and reset lever 37 for movement of the movable contact arm 13 to the adjustable stop which is threaded into the bracket 30. This action is accomplished by actuation of the slotted lever extension portion 38 about the lever pivot at 39 by a pin 41 carried by the actuator lever 42 of the relay armature 36.

The contact actuation extension 43 on the lever arm 42 moves with electromagentic attraction of the armature 26 towards the core 32, and functions to open the normally closed relay contact points 44 and 45. These points are connected through their respective contact arms 46 and 47 to the leads 48 and 49 which are soldered to the external circuit terminals 51 and 52.

When it is desired to connect the time delay system in a circuit arrangement as shown in Fig. 4, the contact points 44 and 45 are constructed in a normally open relationship wherein the contact arm 46 carrying contact point 44 is transposed with respect to the arm 47 which carries contact point 45 and spaced therefrom in such a manner that movement of extension 43 of arm 42 functions to move the arm 47 for contact closure. Such a construction will be apparent to those skilled in the art when taken in view of the schematic illustration thereof in Fig. 4, hereinafter described in greater detail.

The manual delay setting arrangement at 50 of Fig. l is carried by a formed portion of the transparent plastic cover 53 which is provided with a well portion 54 for reception of a spring 55. This spring 55 is restrained by the wall portion 56 and acts to lift the setting knob 57 and maintain it and the reset shaft assembly 58 away from the engagement position for the arm 59 thereof with the contact arm 13.

The arm 59 is suitably retained by the hollow shaft 58 in a manner to permit access through the shaft for screwdriver adjustment of the upper pivot 11 in the nut assembly 2 The bore 60 in the shaft 58 is closed by a plug 61 which is pressed in the top of the knob 57 to prevent the entrance of dust into the mechanism. The reset lever 59 may be attached to the shaft 58 in any desired manner as by the tong shaped arrangement at 69. The reset function is such that the knob 57 is depressed against the spring 55 to provide engagement of the manual reset arm 59 with the moving contact arm 13 and move it away from the fixed contacts 15 and 65 toward the stop 25. The reset arm 59 is thereafter released and lifted away from the arm 13 by action of spring 55 while the rotation thereof to a normal position is accomplished by the spiral spring 62, the inner end of which is fixed to the shaft or to a suitable collar carried by the shaft in a well known manner with the outer end thereof held as by pinning or staking in the slotted post 63.

While a preferred embodiment of the invention has been shown in Figs. 1 and 2 and described in a relationship wherein the coil terminals 29 and 21 of coil 12 are brought out for short circuiting by a circuit which includes contacts 44 and 45, it is to be understood that the invention is equally well adapted for use in short time delay arrangements in which the coil is not short circuited but in which the time delay relationship is accomplished by the back E. M. F. developed in the closed circuit coil support form not shown but of a conventional nature and which supports the coil 12 and moves therewith in the field of the magnet. Also the coil turns may be permanently short circuited at the coil as by soldering at the coil ends. The spring 17 for the relay arm 13 exerts a force sufiicient only to bias the arm to position and maintain the contacts 14 at rest against contact 15 rather than at the center zero position of conventional sensitive relays. The movement of the arm 13 against the torque of the spring 17 to the stop 25 to initiate a time relay may be accomplished by either of the instrumentalities 37 or 59 as desired.

One circuit by which automatic recycling or delay pulsing may be accomplished with a minimum of battery drain and which provides for operation substantially throughout the shelf life of a battery is shownin Fig. 3. This circuit is shown for purposes of illustration and the terminal connections of Figs. 1 and 2 are in agreement with Fig. 3 although the invention is not intended to be limited thereto since other circuit relationships will be apparent to those skilled in the art to which this invention pertains. Also the illustration in Figs. 1 and 2 of certain internal lead connections corresponding to Fig. 3 is not intended to limit the structural arrangementor operation of the device 1 to the circuit shown, nor is the showing of eight external circuit taps or terminals intended to limit the invention to the particular arrangement shown, since a fewer number of terminals and diiferent circuits connections thereto may be used as shown in Fig. 4.

The time delay switching action which is provided across the output terminals, corresponding to 64 through lead 72, contacts 15 and 14, arm 13, spring 17, lead 73 to external terminal 66 of Figs. 2 and 3, may be.

applied to suitable relays or stepping switches to control most or all delay circuitry of an aircraft launched mine or the like.

The operation of the circuit of Fig. 3 is such that energization of the set-reset relay coil 31 with an initial closure of switch 71, which may be an arming switch of the mine if desired, when the arm 13 is at rest with the sets of contacts 14, 15 and 65, 67 closed, functions to ground one side of the coil 31 to provide a discharge path for the normally charged condenser 75. This condenser discharge draws the armature 36 toward the core 32 to open contacts 65 and 67, 15 and 14, as well as 44-, 45 while mechanically moving reset arm 37 about pivot 39, against moving arm 13 to rotatably move the open circuited coil 12 in the field of magnet 4, with only the magnetic force resistance of the metallic coil form for coil 12 until the arm 13 is restrained against the stop 25.

This discharge and setting action is almost instantaneous because of the rapid decay of the condenser 75 through the coil 31 when switch 71 is closed. The

charging circuit for condenser 75 comprises the battery 83, resistance 74 and the winding of coil 31. The battery may advantageously comprise a miniature type dry cell pack of the variety used in miniature radio applications for the 13+ supply. It functions to charge the condenser 75 through the resistance 74 at a rate insufiicient to actuate the relay during the building up of a charge on the condenser. The condenser may be of the nature of a high capacity electrolytic condenser. The condenser charging cycle starts as soon as the shunt connection from the negative battery and condenser junction 77 to ground and hence across the coil and condenser is removed from ground by movement of the arm 13 to open the circuit of lead elements 73, 17, 13 and 76 through contacts 65, 67. While the charging circuit is of long duration in comparison to the condenser discharge cycle for actuation of the relay, the circuit constants are chosen to substantially recharge the condenser 75 during the time delay period of return travel of the short circuited magnetically damped coil 12 and arm 13 which moves therewith, while the arm is not in engagement with the fixed contacts. As the arm 13 returns to a contact closing relationship for the contacts 67, 65 under action of the spring 17, and with the switch 71 remaining in closed relation, the condenser 75 discharges at the instant the contact 67 engages 65. This functions to draw-in the armature 36 and move the reset lever 37 connected thereto, in a manner to reposition the arm 13 adjacent the stop.

The spring 41) which is represented diagrammatically in Fig. 3 and which may in practice advantageously comprise the resilient leaf 47 of Fig. 2, returns the armature lever and reset lever to a non-engaged relationship with arm 13 until a subsequent cycle of coil actuation.

It will be apparent from Fig. 3 that the coil winding 12 is short circuited through lead 28, arm 47, contacts 44 and 45, arm 46, leads 48 and 23, as soon as armature arm 42 is returned by spring 40. Since the period of energization of the relay coil 31 is relatively short due to the short period of discharge of condenser 75 therethrough, the return of the arm 42 by spring 40 is almost instantaneous and the contacts 44- and 45 are closed across the terminals 51 and 26 of coil 12. This provides a time delay as this closed circuit coil 12 is moved by spring 17 back to the contact closing relationship for contacts 14 and 15.

It is thus apparent that in a time delay circuit of the nature disclosed the system becomes automatic to provide time delay pulses across terminals 64, 66 of the damped sensitive relay after an initial closure of switch 71 which remains closed if continuous automatic pulsing function is desired. For one cycle operation such as laboratory time delay applications wherein it is desired to electrically operate the set-reset arm 37 rather than to move the arm 13 by the knob control 50 it is merely necessary to close the switch 71 and thereafter open the circuit after actuation of the armature 32 of the coil 31. Subsequent cycles are obtained merely by closing the switch 71 for each desired actuation.

A somewhat simplified circuit for providing magnetic time delay of the apparatus of the instant invention is shown in Fig. 4 in which the time delay is provided by movement of the metallic coil form for coil 12 through the magnetic field of magnet 4 to produce a back E. M. F. and consequent time delay. In an arrangement of this character, the bias applied to the arm 13 by the spring 17 is adjusted to position the contact 14 against the contact 15. In this circuit the relay arm is connected through spring 17 and lead 73 to external terminal 66 to which one terminal of the battery 85 is connected. The other battery terminal is connected at 78 to one of the terminals for coil 31. The terminal 79 for the return lead of coil 31 is connected to terminal 64. The return lead terminal 7? of coil 31 is connected externally to terminal 64 for connection via leads 72 to. switch contact 15 which makes with contact 14 following return of the arm 13 to a normally closed position by spring 17. It is thus apparent that the coil 31 is energized by battery 85 with each contact making of contact 14 on arm 13 with contact 15. If desired, an on-ofl switch 80 may be inserted in the circuit, as for example, between terminal 79 and 64 in a well known manner.

The external circuit for which the timing pulse is desired, is connected across terminals 51 and 52 which are brought out from the arm 46 and 47' with closure thereacross occurring through contact points 44 and 45'. The switches of this circuit are normally opened in a manner provided by the hereinbefore described modification or transposition of the contact arms 46 and 47 in a manner well known in the art for operation by lever extension 43.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A magnetically damped electrical time delay device comprising a permanent magnet, a movably mounted coil arranged in the field of said magnet, means for cyclically displacing the movable contact a predetermined distance from said fixed contact, a movable contact carried by said coil, a fixed contact adapted for engagement by said movable contact, means for urging said movable contact into a normally closed relationship with respect to said fixed contact, and means for short circuiting the coil following displacement thereof and only during the return movement of said movable contact.

2. A magnetically damped electrical time delay device of the character described comprising, in combination, a movable coil type sensitive relay means of a character having a normally closed movable contact arranged to be responsive to movement of the movable coil, reset means for opening a circuit through the normally closed movable contact, and means for selectively short circuiting the movable coil only during the entire period of return movement of the contact to the normal position thereof thereby to provide magnetically damped time delay.

3. A magnetically damped time delay device comprising, in combination, a permanent magnet movable coil meter type sensitive relay having fixed and movable contacts said movable contact being affixed for movement with said movable coil, actuator means for displacing the movable contact a predetermined distance from said fixed contact, and means for short circuiting the movable relay coil only during the return period of said coil and movable contact to the normal position thereof thereby to provide magnetic damping of the movement thereof.

4. An automatically recycling time delay system of a character incorporating a magnetically damped electrical time delay device comprising a permanent magnet movable coil type sensitive relay having a plurality of fixed contacts, a movable contact adapted to engage said plurality of fixed contacts, said movable contact being connected for movement with said coil, said coil being disposed in the field of said magnet, cyclically operative actuator system means for displacing the movable contact from said fixed contact for initiating an initial cycle of operation, means responsive to a predetermined movement of said movable contact away from said fixed contact to provide a short circuiting of the movable coil to provide a damping thereof only during return movement of the movable contact with said coil to the normal position thereof, and circuit means rendered responsive to completion of return movement of said movable contact into engagement with said fixed contact for automatically reinitiating a subsequent cycle of displacement of said movable contact from said fixed contact.

7 8 5. The structure of the system of claim 4 additionally viding substantially continuous automatic operation of characterized by means in the said circuit means for consaid device after an initial actuation thereof. ditioning the reinitiating means for subsequent coil and References Cited in the file of this Patent contact displacement, said conditioning belng efiected thereby during the time delay period of return movement 5 UNITED STATES PATENTS of said movable contact and coil, and said circuit means 2,039,230 Lamb Apr. 28, 1936 further incorporating a low current drain circuit for pro- 2,648,735 Marshall Aug. 11, 1953 

